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 Regarding warnings while loading lef file.... 

Last post Fri, Jul 20 2012 2:22 AM by Ganga111AtFPS. 2 replies.
Started by Ganga111AtFPS 18 Jul 2012 01:57 AM. Topic has 2 replies and 1494 views
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  • Wed, Jul 18 2012 1:57 AM

    • Ganga111AtFPS
    • Top 500 Contributor
    • Joined on Fri, Jun 29 2012
    • Hyderabad, Andhra Pradesh
    • Posts 21
    • Points 545
    Regarding warnings while loading lef file.... Reply

    VIOLATION IS AS FOLLOWS:

     

     Loading Lef file /remote/home/kakumanu/NEW_BLOCKS/libs/lef/mem/RAM_4096x32.vclef...
    **WARN: (ENCLF-200):    Pin 'Y' in macro 'XOR3XLMVH' has no ANTENNADIFFAREA attribute defined.
    For any non-power/ground input or inout pin, The attribute should be
    defined if any area ratio antenna attribute is defined on any layer.
    **WARN: (ENCLF-200):    Pin 'Y' in macro 'XOR3X8MVH' has no ANTENNADIFFAREA attribute defined.
    For any non-power/ground input or inout pin, The attribute should be
    defined if any area ratio antenna attribute is defined on any layer.
    **WARN: (ENCLF-200):    Pin 'Y' in macro 'XOR3X4MVH' has no ANTENNADIFFAREA attribute defined.
    For any non-power/ground input or inout pin, The attribute should be
    defined if any area ratio antenna attribute is defined on any layer.
    **WARN: (ENCLF-200):    Pin 'Y' in macro 'XOR3X2MVH' has no ANTENNADIFFAREA attribute defined.
    For any non-power/ground input or inout pin, The attribute should be
    defined if any area ratio antenna attribute is defined on any layer.

    Some more warnings i got like this for XOR and XNOR cells ....

    Question:::

    If we dont have  ANTENNADIFFAREA for the pin 'Y' what will be the problem??

    Please respond to this..

    Thanks 

    Gangadhar.

     

    • Post Points: 20
  • Thu, Jul 19 2012 8:09 AM

    • Scrivner
    • Top 100 Contributor
    • Joined on Thu, Oct 9 2008
    • Ridgeland, MS
    • Posts 75
    • Points 1,475
    Re: Regarding warnings while loading lef file.... Reply

     I think the lack of antenna diffusion area defined on the output will make the tool more pessimistic about identifying antenna violation on nets driven by those outputs. Diffusion attached to a net will act as a diode which will drain the charge during manufaturing and reduce the risk of an antenna violation. If the diff is not defined, the tool does not know that the diode exists and may flag a false antenna violation.

     Since this situation is more pessimistic (more likely to assume there is a violation), it will not hurt the design, but may cause you to require extra antenna cells which aren't really needed.

    • Post Points: 20
  • Fri, Jul 20 2012 2:22 AM

    • Ganga111AtFPS
    • Top 500 Contributor
    • Joined on Fri, Jun 29 2012
    • Hyderabad, Andhra Pradesh
    • Posts 21
    • Points 545
    Re: Regarding warnings while loading lef file.... Reply

     Hi ,I just want to discuss with some more details::

    Antenna Ratio = area of gate (poly) / area of metal piece which is connected to that poly.

     

    If the antenna diode is really needed for a particular long net , if the tool can not find the requirement of that diode due to this warning ,how can we find the requirement of that diode for that particular net.Tool only need to fix this antenna diodesif there is  no possibility of layer hopping.

    But , before tape_out we need to fix these also other wise we have to get pain of charge accumulation.

    Thank you,

    Gangadhar.

    • Post Points: 5
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Started by Ganga111AtFPS at 18 Jul 2012 01:57 AM. Topic has 2 replies.